Swimming in gift cards this Christmas? Walmart has just rolled out an exchange program in hopes of profiting from the roughly $1 billion worth of gift cards that remains unused each year.

Shoppers can now cash in unwanted gift cards from roughly 200 retailers, airlines and restaurants in exchange for a Walmart gift card, reportsThe Boston Globe.

The exchange, however, is not dollar-for-dollar. For instance, while Amazon cards can be worth as much 95 percent of their original value, Gap cards are only worth as much as 85 percent. For some retailers, this exchange rate can be as low as 70 percent.

In order to determine the value of their cards, users can log on to Walmart’s dedicated site and enter the merchant name and card balance. After orders are placed, printable eGift Cards are usually emailed within one or two hours, Walmart says.

The pilot program represents a partnership between Walmart and CardCash, an online gift exchange where users can sell their gift cards for cash or buy cards at discounted rates.

If it proves successful, Walmart spokesman Ravi Jariwala told the Globe, then the holiday initiative could become a permanent service.